1. Field of the invention
This invention relates in general to offshore drilling equipment, and in particular to a diverter assembly that utilizes a ball element which has an annular seal for closing on pipe, and which will rotate 90 degrees for full closure when pipe is not located in the diverter assembly.
2. Description of the Prior Art
In offshore drilling, a diverter is normally employed during the early stage of drilling while the well is still shallow and before a blowout preventer is connected. The diverter is an assembly that mounts directly below the rotary table into the upper end of a string of riser or conduit extending upward from the sea floor. The diverter has a packer or seal element that will close around drill pipe or casing extending through the riser. Diverter outlets extend through the diverter housing.
In the event of a pressure kick encountered before the blowout preventer is installed, the operator will close the diverter to seal around the pipe. The drilling fluid is allowed to flow through the conduit and out the diverter outlet. The well fluid is then diverted through the conduit to vent or flare lines where the oil and gas may be safely disposed of or flared.
One type of diverter employs annular insert packers that insert in the housing. Hydraulic pressure forces the elastomeric insert packers radially inward to seal around the pipe. If the pipe is out of the hole, this type of diverter will not seal well across the bore of the diverter passage.
Another type of diverter employs an inflatable type packer that will seal across the bore of the passage when pipe is not located in the diverter housing. That type of diverter will also seal around the pipe. However, it is large and time consuming to rig up with each new well.